1. Field of the Invention
The present invention relates to an image forming apparatus that uses ordinary color toners of yellow, cyan, magenta, and black as well as additional color toners, such as light cyan and light magenta toners, to form a composite color toner image on an intermediate transfer member.
More particularly, the present invention relates to an image forming apparatus that can increase the life of image carriers.
2. Description of the Related Art
Japanese Patent Application Laid-open No. 2002-148893 discusses a conventional image forming apparatus including a plurality of image carriers arrayed along a moving direction of an intermediate transfer member. Yellow, magenta, cyan, black, light cyan, and light magenta toner images are formed on the image carriers respectively.
Such conventional image forming apparatus drives the image carriers of yellow, magenta, cyan, and black toners when an ordinary image is formed (hereinafter, referred to as an “ordinary image formation mode”), while the image carriers of light cyan and light magenta toners are stopped. Stopping the image carriers of light cyan and light magenta during the ordinary image formation mode is effective to prevent the image carriers of light cyan and light magenta toners from being worn out. Thus, the life of the image carriers can be extended.
However, according to the above-described conventional image forming apparatus, while the image carriers of light cyan and light magenta toners are stopped during the ordinary image formation mode, the image carriers of light cyan toner and light magenta toner have to be disengaged or separated from the intermediate transfer member which contacts the image carriers of light cyan toner and light magenta toner at two portions. Thus, the configuration of the conventional image forming apparatus is complicated.